The present invention relates to a particle image analyzing apparatus in which images of particles suspended in a liquid sample are picked up in order to analyze the particles and, more particularly, relates to a particle image analyzing apparatus suitable for analysis of cells or particles contained in blood or urine.
For example, cells or particles contained in blood or urine have been heretofore analyzed by preparing a specific sample on a microscope slide and observing it through a microscope. As for urine, because the concentration of particles in urine is low, a sample of urine is centrifugally condensed by a centrifugal separator before the sample is observed.
There is an apparatus for automatizing these observing and examining operations. In the automatizing apparatus, a microscope slide is smeared with a sample of blood or the like and then set in a microscope. Then, the slide on the stage of the microscope is stopped at a suitable location where particles are present, through automatic scanning. Next, still images of the particles are picked up, so that the classification of the particles in the sample, or the like, is performed by means of characteristic extraction and pattern recognition based on image processing techniques.
An example of the aforementioned automatizing apparatus using microscope slides is an apparatus for automatically reexamining slide samples, described in JP-A 50-68330. In the automatic reexamination apparatus, various kinds of blood corpuscles or the like on microscope slides are analyzed automatically and where the results of automatic analysis are inconclusive, samples are moved to a reexamination position where the samples are reexamined directly by a surveyor or the like.
In the aforementioned automatizing apparatus, however, a long time is required for smearing a microscope slide with a sample. Moreover, extra work is required for detecting particles while moving the stage of a microscope mechanically and for moving the particles to a suitable image pickup zone in the visual field of the microscope. Accordingly, the aforementioned automatizing apparatus requires a long period of time to analyze each sample and comprises complex mechanical construction.
On the other hand, there is a particle analyzing method using a flow sight meter in which particles to be examined are analyzed optically while the particles are suspended in a fluid sample and are moved in a flow chamber continuously without smearing a specific sample over a microscope slide (for example, a method of analyzing particles of a dilute fluid sample as described in JP-A 58-76740). The particle analyzing method using a flow sight meter serves to observe the intensity of fluorescence and the intensity of scattered light from respective particles in a fluid sample and has a processing capacity of 1000 per second.
There is also an analyzing apparatus in which: still images of particles contained in a fluid sample are picked up by means of a flash lamp while the fluid sample is poured into a wide image pickup zone through a specific-form flow path; and the particles are analyzed by using the images thus picked up. In the analyzing apparatus, the flash lamp serving as a pulse light source emits light periodically in synchronism with the operation of a charge coupled device (CCD) camera and images of sample particles are enlarged by a microscope, so that the enlarged images are projected onto the CCD camera. The light-emitting time of the pulse light source is short, so that still images can be picked up even though the fluid sample containing particles is poured continuously.